Case locality: Pure domains and object shift

Languages appear to differ in the locality conditions that regulate nominative Case checking: a dative or ergative subject blocks nominative checking of an object in Faroese and Nez Perce, but not in Icelandic or Hindi. Languages also differ in the effect that object shift has on subject Case: object shift has no effect on subject Case in Icelandic, but causes ergative Case to appear on the subject in Nez Perce. These superficially unrelated effects follow if one violable locality constraint is added to the small set of Case faithfulness and markedness constraints within Optimality Theory. This locality constraint, Pure Domain, requires that the checking domain of a head contain only Cases checked by that head. Differences in the relative rank of Pure Domain with respect to Case faithfulness and markedness constraints produces the cross-linguistic variation noted above. This domain approach to Case locality captures the standard notion that a closer DP can interfere with the checking of a further DP, but it also captures the fact that a further DP can interfere with the checking of a closer DP, if that further DP is close enough, a situation that arises with object shift.